This invention relates to a transducer assembly for a magnetic recording system such as a disk drive. More particularly the invention relates to an assembly where the transducer is dynamically loaded onto a rotating disk.
In digital systems, such as in a data processing apparatus, disk drives are used as the means for storing large amounts of data that can be quickly read into or written from a computer's main memory. In a disk drive, a disk, having a magnetic coating on its surfaces, is rotated on a spindle at a predetermined speed. An electromagnetic transducer, also called head, is positioned in close proximity to one of the disk surfaces at a predetermined distance from the spindle to either read data (i.e., playback) or write data (i.e., record) along the circular track defined on the disk surface by the rotary motion of the disk with respect to the transducer. By controlling the position of the transducer, a plurality of concentric tracks on the disck surface are defined.
The head is mounted on an aerodynamic member, usually called slider, which is designed to ride over the air flow created by the rotating disk in order to maintain the head at a predetermined distance from the disk surface. To increase the storage density of the disk smaller head/slider assemblies have been used in order to increase the flux density and reduce the area required to store one bit of information.
The slider is mounted on an actuator arm which in turn is mounted on an actuator motor. The actuator motor moves the arm to successively position the head at predetermined locations (i.e., tracks). Both linear and rotary actuator motor/arm assemblies have been used. In a linear assembly, the actuator arm, and therefore the head, is moved linearly along a radius of the rotating disk, while in a rotary assembly, the actuator arm rotates along an axis parallel to the disk spindle at a point close to the outside rim of the disk. In either case, the slider is suspended from the actuator arm, in order to allow the slider to assume the correct attitude over the air bearing, and the suspension support/slider assembly is cantilevered from the more rigid actuator arm. The motion of the slider can be resolved along three mutually orthogonal axes called the pitch, roll and yaw axes. The pitch axis is defined as the transverse axis of the slider, the roll axis is defined as the longitudinal axis of the slider and the yaw axis is normally defined as the vertical axis, assuming that the slider is placed on an horizontal plane, and is mutually orthogonal with the pitch and roll axes. To allow the slider to move freely over the disk surface the cantilevered suspension must provide a low spring rate along the yaw axis. To this end, an elongated cantilevered leaf spring is used. The geometry of the cantilevered spring, however, provides low stiffness not only along the yaw axis of the slider, but also in a direction transverse to the spring's longitudinal axis. This lack of lateral rigidity results in a low frequency resonance characteristic for the cantilevered suspension. This means that, in response to lateral forces exerted on the suspension, the suspension vibrates about its nominal position and consequently interferes with the proper positioning of the head at the selected track. This lack of lateral rigidity might be tolerated in applications using a linear actuator arm since the nominally linear motion along the longitudinal axis the cantilevered suspension spring minimizes the development of lateral forces. However in applications requiring a rotary actuator arm, the combination of arcuate motion and centrifugal force unavoidably generates lateral forces on the cantilevered spring. These lateral forces push the head off its nominal position and interfere with its proper operation. The weight of the suspension assembly, i.e. the suspended mass, further adds to the resonance problem, as well as to the torque requirements of a rotary actuator motor.